The present invention relates generally to a golf ball, and a method of manufacturing the golf ball. In particular, a cover layer on the golf ball includes areas having a higher hardness and areas having a lower hardness.
The game of golf is an increasingly popular sport at both the amateur and professional levels. A wide range of technologies related to the manufacture and design of golf balls are known in the art. Such technologies have resulted in golf balls with a variety of play characteristics. For example, different golf balls are manufactured and marketed to players having different golfing abilities, such as different swing speeds.
Similarly, a golfer may use different golf balls having different play characteristics depending on the golfer's preferences. For example, different dimple patterns may affect the aerodynamic properties of the golf ball during flight, or a difference in the hardness of the cover layer may affect the rate of backspin. With regard to hardness in particular, a golfer may choose to use a golf ball having a cover layer and/or a core that is harder or softer. A golf ball with a harder cover layer will generally achieve reduced driver spin, and achieve greater distances. However, a harder cover layer will generally cause a lower rate of spin, such that the golf ball will be better for drives but more difficult to control on shorter shots. On the other hand, a golf ball with a softer cover will generally experience more spin and therefore be easier to control and stop on the green, but will lack distance off the tee. Soft cover layers are generally described as having a good “feel.”
A wide range of golf balls having a variety of hardness characteristics are known in the art. Generally, the hardness of a golf ball is determined by the chemical composition and physical arrangement of the various layers making up the golf ball. Accordingly, a number of different golf ball materials are mixed and matched in various combinations and arrangements to create golf balls having different hardness values and different hardness profiles.
However, designing golf balls to achieve desired hardness characteristics suffers from at least several difficulties. Generally, the construction of known golf balls requires that a wide range of design variables such as layer arrangement, materials used in each layer, and layer thickness be balanced against each other. Changes to any of these variables may therefore improve a desired hardness only at the expense of other play characteristics.
For example, the hardness of a cover layer may be controlled by forming the cover layer from a mixture of two or more polymer materials. However, if the cover layer is made from more than one polymer material, the polymers are conventionally mixed or blended together. Such mixing is necessary so that the materials may be used in a compression molding or injection molding process to form the cover layer. Namely, in order to inject a material made from two ionomer resins (such as one resin having a Shore D hardness of 60 and another resin having a Shore D hardness of 40) for a cover layer, known processes necessitate first mixing the two ionomer resins, and then melting the two ionomer resins for injection. During the melting process, the two ionomer resins are so well mixed that the finished product of the cover layer is regarded as one unitary material. Therefore, the play characteristics of the cover layer are limited due to the unitary construction of the cover layer.
Additionally, materials costs and design costs associated with known golf ball constructions may unduly increase the cost of the golf ball to the end consumer. Perhaps most importantly, known golf balls generally cannot simultaneously achieve the advantageous play characteristics associated with high cover hardness (greater distances) while also achieving the advantageous play characteristics associated with low cover hardness (good feel).
Therefore, there is a need in the art for a system and method that addresses the shortcomings of the prior art discussed above.